Gymnothorax parini, a new species of moray eel (Teleostei: Muraenidae) from Walters Shoals, Madagascar Ridge

7 Pages·1991·2.9 MB·English

by  Bruce B Collette

PROC. BIOL. SOC. WASH.
104(2), 1991, pp. 344-350
GYMNOTHORAXPARINI, A NEW SPECIES OF
MORAY EEL (TELEOSTEI: MURAENIDAE) FROM
WALTERS SHOALS, MADAGASCAR RIDGE
Bruce B. Collette, David G. Smith, and Eugenia B. Bohlke
Abstract.—Gymnothoraxpariniis described from 19 specimens collected in
shallow water (18 m) at Walters Shoals in the southwestern Indian Ocean. It
is distinctive in having a wide bright white margin on the dorsal, caudal, and
anal fins; a long anterior nostril tube that reaches or passes the edge of the
upperlipwhendepressedventrally;andatleasthalftheposteriornostrillocated
anterior to the anterior margin ofthe eye. It resembles several other species
found around islands in the subtropical zone ofthe southern Indo-Pacific, but
differs from all ofthem in color pattern, number ofvertebrae (143-152), and
position ofthe posterior nostril.
During Cruise 17 of the Soviet oceano- ology, Moscow(lOAN). Otherinstitutional
graphicresearch vessel Vityazin December acronyms follow Leviton et al. (1985).
1988,theshallow-waterfishfaunawassam-
palneddbwyithhotorkapsa,nfdishlitnreawfliss,hiSniggs(bCeoellettrtaewls&, Gymnothoraxparini, new species
Parin 1991).Amongthefishescollectedwere Figs. 1-3
anew species ofScorpaenodesdescribed by Holotype.-US^M 307751 (female, 538
Poss&Collette(1990)andanewmorayeel, mm TL): western Indian Ocean, Walters
which is described herein. Walters Shoals, Shoals;depth 18m; VityazCr. 17,sta.2751,
an isolated, submerged, oceanic mountain- BBC 1923, 22 Dec 1988.
m
top that rises to within 18 ofthe surface, Paratypes.—All from Walters Shoals, 18
is located 400 nautical miles south ofMad- m, VityazCruise 17, December 1988.ANSP
agascar and 600 nm east ofSouth Africa at 163850 (2, 545-655), same data as holo-
USNM
33°09-16'S, 43°49-56'E. Thepurposeofthis type. 307749 (2, 480-590), Vityaz
paper is to describe the new species so that 2695a, BBC 1906, 13 Dec 1988. USNM
the name is available for subsequent anal- 307750 (1, 575), Vityaz 2715, BBC 1914,
USNM
ysisoftheWalters Shoalsfishfaunaandthe 16 Dec 1988. 307752 (4, 588-650),
other West Wind Drift islands and sea- lOAN uncat. (3, 573-720), AMS 1.28155-
mounts, and to compare it with other sim- 001 (3, 585-665), and LACM 44749-1 (3,
ilar species ofthe genus Gymnothorax. 665-695), Vityaz 2683b, BBC 1901, traps,
Materials and methods.—Connis and 11 Dec 1988.
—
measurements follow Bohlke (1989). Ma- Diagnosis. Gymnothorax parini is dis-
terial is deposited in collections ofthe Na- tinguished from other species ofthe genus
tional Museum ofNatural History, Wash- bythe followingcombination ofcharacters:
ington, D.C. (USNM); AcademyofNatural anal finwith bright white distal margin and
Sciences of Philadelphia (ANSP); Austra- dark,unpattemedbasalportion;whitemar-
lian Museum, Sydney (AMS); Natural His- gin conspicuously continuous around cau-
tory Museum of Los Angeles County dal fin and on to dorsal fin, somewhat less
(LACM); and Shirshov Institute ofOcean- intenseanteriorly; anteriornostrilverylong.
VOLUME 104, NUMBER 2 345
Fig. 1. Gymnothoraxparini,newspecies, Vityazsta.2683.Knifeis90mmlong.(Photographproducedfrom
colorslide used forcolorplate lain CoUette &Parin 1991.)
reaching upper lip when depressed ventral- upper jaw 41.2-52.7 (18). Of upper jaw:
ly; at least halfofposterior nostril located snout 41.0-47.2 (19).
anterior to vertical line through anterior Body moderately elongate, typical of
marginofeye;bodydarkwithirregularlight Gymnothorax, with anus slightly before
markings; snout moderately long; all teeth midbody. Headandsnoutmoderatelyelon-
uniserial;andmeanvertebralformula4-56- gate,jawsclosecompletely. Dorsalfinorigin
147. immediately posterior to occiput, well an-
Description.—Total vertebrae 143-152, terior to gill opening. Eye moderate in size,
X= 147 (« = 19), predorsal vertebrae 3-5, locatedapproximatelyovermiddleofupper
X= X=
3.8 (19), preanal vertebrae 53-58, jaw. Fins relatively low, dorsal somewhat
55.7 (19). Vertebral counts for holotype 4, higher than anal. Anterior nostril long and
58, 151. Pores:branchial2(13),mandibular tubular, when depressed ventrally reaches
6-7 (16), infraorbital 4 (16), supraorbital orpassesedge ofupperlip. Posteriornostril
1+2(16). Teeth: upperjaw6-18(19), lower without prominentraised rim, located over
jaw 10-17 (19), median intermaxillary 1-4 or slightly anteriorto level ofanterior mar-
(19), vomer 4-14(16). gin ofeye, at least halfofnostril anterior to
%
Proportions as of TL: preanal 43.2- vertical line with anterior margin ofeye.
46.6 (19), predorsal 9.3-13.0 (15), head Pores in lateralis system small and in-
12.4-14.7 (18), depth at anus 4.5-6.1 (16). conspicuous and arranged in typical Gym-
Of head length: snout 19.1-23.3 (18), eye nothoraxpattern (Fig. 2). Two in branchial
7.7-11.2 (18), interorbital 10.3-14.0 (18), section of lateral line, anterodorsal to gill
346 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
Fig. 2. LateralviewofheadofholotypeofGymnothoraxparini, newspecies(USNM 307751, 538 mmTL)
toshowcephalic laterallinepores.
opening. Sixporesinmandibularcanal(one a few tiny teeth set between large anterior
specimen with seven on one side), all an- teeth. Vomerine teeth small, triangular,
teriortorictus. Allfourporesininfraorbital pointed, mainly uniserial but occasionally
canal located along upperjaw between an- one or two teeth displaced to side. Clear
terior nostril and vertical with posterior difference between males and females in
marginofeye.Threesupraorbitalpores: one number ofteeth (Table 1), with males hav-
(ethmoidal pore) at tip ofsnout on edge of ingfewerupper-jaw,lower-jaw,andmedian
upper lip, one adjacent to base ofanterior intermaxillary teeth.
nostril, and one posterodorsal to anterior Ground color in alcohol dark brown, al-
nostril. most black, overlain with irregular, light
All teeth smooth, without serrations of brown markings with erratic borders and
anykind (Fig. 3). Lateral teeth in upperjaw mottled within by darker brown. Intensity
narrowly triangular, slightly compressed, and extent oflight markings variable; some
somewhat recurved, and uniserial; maxil- specimens nearly uniformly black, others
lary and intermaxillary series confluent, with extensive light areas, but overall im-
without obvious demarcation. Peripheral pression dark with light markings. Pale ar-
intermaxillary teeth increase in size from eas sometimes form irregular bars, some-
anteriortoposterior;anteriormaxillaryteeth times snowflake- or lichen-like patches.
approximately same size as posterior inter- Head usually lighter than body, without
maxillary teeth, becoming progressively patchwork pattern oflight markings, often
smallerposteriorlyandalso somewhatmore irregularlymottledwithdarkerbrown.Anal
steeplyinclinedinposteriordirection.Afew finmarkedconspicuouslywithbrightwhite
tinyteethsetimmediatelybeforeand/orbe- margin,whichhasabluishcastinlife; basal
hind large intermaxillaryteeth. One to four part offin uniformly dark brown or black,
large, slender, sharply pointed, depressible without markings. Dorsal fin colored sim-
fangsonmidlineofintermaxillaryplate, in- ilarly, but narrower white edge tends to be
creasing in size from anterior to posterior. interruptedanteriorlyinsmallerspecimens;
Teeth in lower jaw similar in size and ar- basal part ofdorsal fin dark, but some light
rangementtothoseofupperjaw, largestan- markingsencroachuponitfrombody.White
teriorly and decreasing in size posteriorly; marginconspicuousaroundcaudalfin. Skin
VOLUME 104, NUMBER 2 347
Table1.—NumberofteethinmaleandfemaleGym-
nothorax parini, expressed as total number, right +
left, in upperandlowerjaws(numberofspecimensin
parentheses).
Median
Upperjaw Lowerjaw intermaxillary
Females 30-32(5) 29-32(4) 3^(5)
Males 19-26(8) 24-30(7) 1-2 (8)
immediately around gill opening tends to
be dark, but without conspicuous spot
around it. Some dark pigment at comer of
mouth, butnotformingaconspicuousspot.
Sensory papillae on head small, each set in
atinydarkspot,forminginconspicuouspat-
tern ofrows.
Sex and sexual dimorphism.—Ofthe 19
specimens ofGymnothoraxparini, five, in-
cluding the holotype, are clearly females
mm
(538-650 TL), eight are males (480-
720 mm), and the sex ofthree was not de-
termined.Althoughtheovariesareenlarged
and the eggs conspicuous, none of the fe-
malesisinspawningcondition.Atleastfour
other species ofGymnothorax show a sim-
ilar sexual dimorphism in the number of
teethas reportedhere for G. parini: G. rich-
ardsoni(HsXodk.'a. 1986), G. enigmaticusand
G. cf. monochrous (M. A. Gibbs, pers.
comm.), and G. chilospilus (D. G. Smith,
work in progress). Hatooka also reported
dimorphism in the dentition oftwo species
ofEchidna, and Gibbs has found another
case in Enchelycore schismatorhynchus.
Sexual dimorphism in tooth number may
be widespread among morays and deserves
further study. In the case of G. chilospilus,
the female tooth pattern is also thejuvenile
pattern; the maleschangeat maturity. With
material available, we cannot determine
whether G. parinifollows the same pattern.
ni,Finge.w3.speDceinetsi(tiUoSnNofMho3l0o7t7y5p1e,of53G8ymmnomthToLr)a.xpari- Aberrant specimen.—Of the 20 speci-
mens ofGymnothorax collected at Walters
Shoals, one (USNM 307753, Vityaz station
2695) stands apart from the others in sev-
348 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
eral ways. The most striking difference is Distribution.—KnownonlyfromWalters
thelownumberofvertebrae,4-52-132. The Shoals in the southwestern Indian Ocean.
m
total is 11 vertebrae fewer than for any of Collectedfrom depths of18 bytraps and
the G. parini and 15 fewer than the mean by hook and line. No morays have been
value for 19 specimens. Ifan eel loses part reported from any ofthe other six islands
ofits tail, it will regenerate a caudal fin, but and seamounts extending along the West
this new structure never looks exactly like Wind Drift between Gough and Tristan da
the original. Ifthis specimen had lost 10- Cunhain the South Atlanticto Amsterdam
15 caudal vertebrae, it would be obvious and St. Paul in the southwestern Indian
from the radiograph, but this specimen Ocean.
shows no evidence ofa regenerated caudal Etymology.—Namedinhonorofourdis-
fin; the entire caudal skeleton appears per- tinguished colleague Nikolai Parin, an ex-
fectly normal. The specimen further differs pertonthe fish faunaofseamountsand sci-
from the others in color. Whereas G. parini entific leader ofcruise 17 ofthe Vityaz, on
were very dark, nearly black, when freshly which all the material of this species was
collected, this specimen was distinctly collected.
brown. Even in preservative this difference Comparisons.—Gymnothorax parini is
isapparent. Inaddition, unlikein G. parini, one of several similar species occurring
thereisasmallbutdistinctdarkspotaround around islands in the subtropical zone of
thegillopening, andthegroovesaroundthe the southern Indo-Pacific region that have
neck and throat are streaked with darker a prominent white margin on the anal fin
brown. Finally, the upper jaw length and and sometimes on the dorsal fin.
interorbital width are slightly higher than Gymnothorax woodwardi McCulloch,
comparable values noted in G. parini, and from Western Australia, is the closest geo-
the snout length as percent of upper jaw graphic neighbor ofG. parini, and the only
length is less in this specimen. speciesinthisgroup thatisknown from the
We do not know how to interpret this Indian Ocean. Unlike G. parini, G. wood-
specimen. It is sufficiently distinct from the wardi has the posterior nostril entirely pos-
others that we have excluded it from the teriorto a vertical line through the anterior
type series, yet with only one specimen we margin ofthe eye. The color pattern ofthis
hesitate to describe it as a second species. species differs in that the trunk pigmenta-
We leave the problem unresolved for the tionconsistsofdarkreticulationsonalight-
time being and provide some counts and erbackground, confined mainly to the dor-
USNM
measurements: 307753, male, 570 sal half, changing to a series of irregular
mm mm
TL, preanal 265 (46.5% TL), pre- bar-like markings on the tail. The white
mm mm
dorsal 65 (11.4% TL), head 76 margin is prominent on the anal fin and on
mm
(13.3% TL), depth at anus 34 (6.0% most ofthe dorsal fin, but the submarginal
mm
TL), snout 16.3 (21.5% HL, 37.9% up- dark band is only weakly developed. There
mm
per-jaw length), eye 8.2 (10.8% HL), are 132-139 vertevrae. Twosyntypes(AMS
mm
interorbital 11.1 (14.6% HL), anterior 1.12224-5)have4predorsal, 56-58preanal,
mm MVF
nostril 3.7 (4.9% HL), vertebrae 4-52- and 135-137 total vertebrae, 4-57-
132, cephalic pores as in G. parini. Teeth 136.
damaged, approximately 16 on left side of Gymnothorax annasona Whitley occurs
upper jaw and 1 1+ on right; 20 teeth on at Lord Howe Island and Middleton Reef,
rightsideoflowerjaw,leftsidetoodamaged both on the Lord Howe Rise. Its snout is
tocount; medianintermaxillaryteeth2; vo- somewhat shorter and deeper than that of
merine teeth 8. G. parini, the anterior nostril is slightly
:
VOLUME 104, NUMBER 2 349
shorter, and the posterior nostril is located lightyellowish gray, with faint darker retic-
entirely over the eye. The basal part ofthe ulations and blotches. There is a submar-
anal fin is patterned, and the body color is ginaldarkbandonbothdorsalandanalfins,
different, consisting of moderately large butbasallybothfinsarepatterned. Thedor-
spots separated by a densely speckled ma- sal profile ofthe snout is flatterthan that of
trix. The holotype (AMS IA.6867) has 58 G.parini, whichtendstobe slightlyconvex.
preanal and 133+ total vertebrae (tail tip Two specimens from Juan Fernandez Is-
missing); two other specimens have 4, 56- land (USNM 88679 and 88680, 810 and
mm
57, 141-143. 824 TL) closely resemble G. bathyphi-
Gymnothoraxnubilus(Richardson),from lus but they are dark brown instead oflight
Norfolk Island, differs primarily in color. gray, with a few indistinct darker spots on
Its body is brown (a rich, chestnut color in thedorsalpartofthebodyanddarkerstreaks
the small specimen examined by us) with on the throat. Both specimens have fewer
irregular cloud-like markings of darker teeth in the upper and lowerjaws than the
brown, more orlessconspicuous. There are type ofG. bathyphilus (13-16 vs. 20-22 re-
threeconspicuousdarkstreaksonthethroat, spectively in the upper, and 15-17 vs. 21-
the dorsal one runningposteriorly from the 23 in the lower). The one intact specimen
comer ofthe mouth; a midventral streak is has 149 vertebrae vs. 145 in the type ofG.
also present. The dorsal and anal fins have bathyphilus.
a dark submarginal band basal to the white One northern hemisphere subtropical
edge. Theholotype(BMNH 1972.1.26.159) species, Gymnothorax kidako (Schlegel)
has3-52-132vertebrae.Ayling&Cox(1982: from Japan, resembles G. parini in body
92, pi. 6) reported this species from north- color and white-margined anal fin. In this
em NewZealand, buttheir description and species, however, thesnoutisslightlyshort-
illustration suggest that it may not be iden- er, the anterior nostril is located entirely
tical to the G. nubilus ofRichardson. overthe eye, and there are 142 vertebrae in
Gymnothorax eupterus (Giinther), from the specimens radiographed.
Raoul Island in the Kermadecs, was de- Several other species have white-mar-
scribed as having white-margined fins and gined anal fins, buttheyeitherlackawhite-
"gular folds and angle of the mouth dark margineddorsalfinortheyhaveotherchar-
brown" (Giinther, 1870:123). Theholotype acters that readily separate them from G.
(BMNH 1855.8.16.50) has 4-52-134 ver- parini.
tebrae. This seems very similar to G. nu- Ofall the preceding species, Gymnotho-
bilus. raxparini seems most similarto G. nubilus
Gymnothorax nasuta De Buen is known and G. bathyphilus. These have the most
fromEasterandPitcaimislands(Randall & slendersnoutsandthemostprominentwhite
McCosker 1975:28). Ithasashorterandless margins on the fins. Both have dark sub-
slender snout than G. parini and fewer ver- marginal bands on the fins immediately
tebrae(138-139,Randall&McCosker 1975 basaltothewhitemargins,thoughnarrower
23). The white margin is weakly developed than that ofG. parini, which covers the en-
on the dorsal fin and around the end ofthe tire basal portion ofthe anal fin. Moreover,
tail. The basal parts of both fins are pat- both specieshavelonganteriornostrils that
terned. The body is dark and speckled with reach the edge of the upper lip, and both
small, irregular white spots, sometimes have the posterior nostril located over or
forming poorly defined patches. anterior to the anterior margin of the eye.
Gymnothorax bathyphilus Randall & In addition, all threehavethe small sensory
m
McCosker, from 250 offEaster Island, is papillae on the head set in tiny black spots
350 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
formingpatternsofrows,althoughtheseare and J. B. Hutchins (WAM) loaned us ad-
somewhat less prominent in G. parini than ditionalcomparativematerial. M. A. Gibbs
in the others. (Moss Landing Marine Laboratory) kindly
None of the above species extends into sharedherunpublishedinformationonsex-
the tropical zone and, except for Gymno- ualdimorphisminmuraeniddentition. Fig-
thorax woodwardi, none occurs onthe mar- ures2and3weredrawnbyKeikoHiratsuka
gins of continents. They seem to be ele- Moore. Drafts ofthe manuscript were read
ments of a fauna peculiar to subtropical by T. A. Munroe and A. B. Williams.
islands of the southern Indo-Pacific. This
whole area has been poorly sampled using Literature Cited
methods likely to capture these eels (traps,
hook and line in moderately deep water), Ayling,seTa.,fi&sheGs.oJf. NCoexw.Ze1a9l8a2n.d.CoClollliinnss:guAiudcektloantdh,e
therefore any general conclusions on bio- Sydney, London, 343 pp.
geography would be premature. We suggest Bohlke, E. B. 1989. Methods and terminology. In
—
thattheseislands andreefswouldbe prom- Fishes of the western North Atlantic. Sears
ising areas for future investigation. FoundationforMarineResearchMemoir1,Part
ComparaAtiMvSe material. —Gymnothormamx Collette9,:1B-.7.B., & N. V. Parin. 1991. Shallow-water
annasona: IA.6867(holotype, 500 fishes ofWalters Shoals, Madagascar Ridge.—
AMS
TL), Middleton Reef. 17369-006 (1, BulletinofMarineScience 48:1-22.
485), BPBM 1477 (1, 540), BPBM 14838 Giinther, A. 1870. Catalog offishes in the British
(1, 340), Lord Howe Island. Gymnothorax Museum, vol. 8, 549 pp.
USNM Hatooka,K. 1986. Sexualdimorphismfoundinteeth
cUfSbNatMhyphilus: 88679 (1, 810) and ofthreespeciesofmorayeels.—JapaneseJour-
88680 (1, 824), Juan Fernandez Is. nal ofIchthyology 32:379-385.
Gymnothorax kidako: USNM 71825 (1, Leviton, A. E., R. H. Gibbs, Jr., E. Heal, & C. E.
445) and USNM 71826 (1, 540), Misaki, Dawson. 1985. Standardsin herpetologyand
Japan. Gymnothoraxnasuta:USNM 65521 ichthyology:part1.Standardsymboliccodesfor
(1, 652N),MNEaZster Island. Gymnothorax nu- ainnsdtiitcuhttiohnyaollorgeys.o-urCcoepceoillaec1t9i8o5ns:8i0n2h-e8r3p2e.tology
bilus: P.1 1717 (1, 287), NorfoWlkAIMs- Poss, S. G., & B. B. Collette. 1990. Scorpaenodes
land. Gymnothorax woodwardi: immaculatus,anewspeciesofscorpionfish(Os-
13263 (holotype, 515), Houtmans Abrol- teichthyes: Scorpaenidae)fromWalthersShoals,
hos. Western Australia. WAM 27949-021 ingsoftheBiologicalSocietyofWashington 103:
543-549.
(3, 1W29A-2M28), Jurien Bay, Western Austra- Randall, J. E., &J. E. McCosker. 1975. The eels of
lia. 28523-001 (1, 385), Augusta, Easter Island with a description ofa new mo-
Western Australia. ray.—ContributionsinScience,NaturalHistory
Museum ofLosAngelesCounty 264:1-32.
Acknowledgments
N. V. Parin kindly invited B. B. Collette (BBC) National Marine Fisheries Service
toparticipateinthecruiseofthe Vityazthat Systematics Laboratory, National Museum
resulted in collecting the material of this of Natural History, Washington, D.C.
new species ofGymnothorax. J. R. Paxton 20560; (DGS) Division ofFishes, National
and his staff at the AMS made material Museum ofNatural History, Washington,
available for examination and had the ho- D.C. 20560;and(EBB)AcademyofNatural
lotype of Gymnothorax annasona x-rayed. Sciences, 19th&theParkway,Philadelphia,
J. E. Randall(BPBM), C. Roberts(NMNZ), Pennsylvania 19103.